Attention deficit hyperactivity disorder (ADHD) is a developmental disorder characterized by inattentiveness, motor hyperactivity and impulsivity. According to neuroimaging data, the neural substrate underlying ADHD seems to involve fronto-striatal circuits and the cerebellum. However, there are important discrepancies between various studies, probably due to the use of different techniques. The aim of this study is to examine cerebral gray (GM) and white (WM) matter abnormalities in a group of ADHD children using a voxel-based morphometry protocol. The sample consisted of 25 children/adolescents with DSM-IV TR diagnosis of ADHD (medicated, aged 6-16 years) who were compared with 25 healthy volunteer children/adolescents. ADHD brains on an average showed a global volume decrease of 5.4% as compared to controls. Additionally, there were regionally specific effects in the left fronto-parietal areas (left motor, premotor and somatosensory cortex), left cingulate cortex (anterior/middle/posterior cingulate), parietal lobe (precuneus bilaterally), temporal cortices (right middle temporal gyrus, left parahippocampal gyrus), and the cerebellum (bilateral posterior). There were no differences in WM volume between ADHD children and control subjects. The results are consistent with previous studies that used different techniques, and may represent a possible neural basis for some of the motor and attentional deficits commonly found in ADHD.
"These brain regions are known to mediate the cognitive control functions that are impaired in the disorder (Huizinga, Dolan, & van der Molen, 2006). Thus, reduced volume and cortical thickness have been observed in several frontal brain regions, in temporal-parietal areas, the basal ganglia, posterior cingulate, the cerebellum, and the splenium of the corpus callosum (Batty et al., 2010; Carmona et al., 2005, 2009; Castellanos et al., 2002; Mackie et al., 2007; Shaw et al., 2006). Despite the amount of working memory studies, EAM has been little examined in children with ADHD. "
[Show abstract][Hide abstract] ABSTRACT: Background Episodic autobiographical memory (EAM) has not been extensively investigated in children with attention-deficit/hyperactivity disorder (ADHD). The objective of this study was to examine EAM in school age children with ADHD in reference to the encoding period: recent memories (previous school years) and remote memories (first years of life).
Methods A sample of 29 children with ADHD and 29 typically developing children, matched for age and gender, completed a questionnaire to assess EAM. These participants were recruited from an initial sample of 572 participants. Developmental differences in accessing and recalling specific personal events and episodic details in groups with ADHD were predicted.
Results The control group showed a typical trend of EAM with fewer remote and episodic memories than recent ones. The ADHD groups showed a general EAM deficit. More precisely, the ADHD-I group performed equally poorly on remote and recent EAMs, whereas the ADHD-C group showed a higher number of remote EAMs than recent ones.
Conclusions The findings suggest that EAM can be impaired in children with ADHD. Clinical and medicolegal implications of these results and the relation between age and childhood amnesia are discussed.
"There are fewer known group level abnormalities in white matter as it is less frequently investigated using structural MRI [Hermann et al., 2007]. Although no differences in white matter volume were reported in one small study [Carmona et al., 2005], a larger study described significantly reduced total white matter volume and significant reductions in the frontal, parietal, temporal, and occipital lobes in ADHD [Castellanos et al., 2002]. Hermann et al.  reported a significantly decreased brainstem volume in patients with both ADHD and epilepsy compared with a healthy control group and a patient group with epilepsy alone compared with the control group. "
"This finding is consistent with a previous voxel-based morphology study that found temporal polar gray matter reductions in children with ADHD, even after accounting for the effect of ODD and CD comorbidity (Sasayama et al., 2010). Likewise, structural and functional OFC abnormalities have been found in ADHD samples without comorbidity of negativism or oppositional disorder (Carmona et al., 2005; Lee et al., 2005). These results therefore suggest that temporal pole and OFC are important in ADHD, irrespective of the presence of comorbid conduct disorders. "
[Show abstract][Hide abstract] ABSTRACT: Structural and functional brain studies on attention deficit/hyperactivity disorder (ADHD) have primarily examined anatomical abnormalities in the prefronto-striatal circuitry (especially, dorsal and lateral areas of the prefrontal cortex and dorsal striatum). There is, however, increased evidence that several temporal lobe regions could play an important role in ADHD. The present study used MRI-based measurements of cortical thickness to examine possible differences in both prefrontal and temporal lobe regions between medication-näive patients with ADHD (N=50) and age- and sex-matched typically developing controls (N=50). Subjects with ADHD exhibited significantly decreased cortical thickness in the right temporal pole and orbitofrontal cortex (OFC) relative to healthy comparison subjects. These differences remained significant after controlling for confounding effects of age, overall mean cortical thickness and comorbid externalizing conditions, such as oppositional defiant and conduct disorders. These results point to the involvement of the temporal pole and OFC in the neuropathology of ADHD. Moreover, present findings add evidence to the assumption that multiple brain regions and psychological processes are associated with ADHD.
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